**Abstract**

Insecticide resistance is a major threat to vector control programmes as insecticides still remain the most effective method to control the vector-borne diseases. For effective management of insecticide resistance, a knowledge of the insecticides used along with their mode of action is a prerequisite to optimize their use. Nowadays, different detection methods, *viz.,* phenotypic, genotypic and proteomic assays are used for assessment of insecticide resistance in vectors. An understanding of the phenotypic and genotypic variations present in the vectors help in implementation of these techniques to evaluate the usefulness of insecticides in an area and to determine the efficacy of an ongoing vector control programmes. The understanding of different factors involved in emergence of insecticide resistance and the alternative solutions to control this problem by the use of rotational, mixture of insecticides and use of piperonyl butoxide to increase the efficacy of indoor residual spray and insecticide treated bed nets are some of the steps taken to tackle the problem of insecticide resistance in vectors.

**Keywords:** insecticides, resistance, vectors, parasitic infections, bioassays

## **1. Introduction**

Many fatal disease-causing pathogens are transmitted to humans by insects which belong to the phylum "Arthropoda". These insects are known as vectors when they harbor the causative organisms in them and transmit it to other humans and animals. Most of the vectors have blood-sucking mouth parts and can transmit pathogens like parasites, viruses and bacteria. The vector-borne diseases are one of the significant causes of morbidity and mortality, particularly in the endemic regions of the tropical and subtropical nations [1], and affect more than 80% of world population. Numerous parasitic infections such as malaria, babesiosis, trypanosomiasis, leishmaniasis and filariasis which affect vast human populations are transmitted by these vectors. For most of these diseases, there is still no effective vaccine is available and a significant strategy to prevent and control these diseases is the control of their vectors by using different methods [2].

Among the various methods used for the control of vector-borne diseases, the most effective and common method is the use of insecticides. All the vector control programmes depend upon the use of insecticides in the form of larvicides, adulticides and insecticide treated nets [3]. It is not easy to say when insecticides

were first used for vector control, but at least since 1000 BC people have been using natural chemicals, i.e., inorganic sulfur against the pest insects [4]. The first chemical insecticide synthesized for the control of medically important vector mosquito, which transmits malaria, was DDT in 1874. DDT was continuously use for the control of different pest insects until the first half of the 20th century, when due to development of resistance it was replaced by other insecticides such as organophosphates and carbamates [5]. The main hindrance to achieve success in vector control programmes is the development of insecticide resistance due to their overuse. Such resistance has a direct effect on the vector in terms of its longevity, infectiousness and on the management of disease [6].
